bug 521406, restructure handlePushes and add transactions to be more failsafe and fight races, r=gandalf
bug 521406, restructure handlePushes and add transactions to be more failsafe and fight races, r=gandalf

Pike/elmo,AdrianGaudebert/elmo,Pike/elmo,AdrianGaudebert/elmo,mozilla/elmo,Pike/elmo,mozilla/elmo,mozilla/elmo,AdrianGaudebert/elmo,mozilla/elmo,Pike/elmo